1. Create a Local User Group with User Type = RADIUS users - leave "User Profile Attribute" and "VLAN ID" blank2. Create Local Users which belong to the Local User Group3. Create an Aerohive AAA Server, in the Database settings check the Local Database and specif the the Local User Group.4. Create an AAA Client which is pointing to the Aerohive AAA Server5. Create a Captive Web Portal with Registration type = User Authentication6. Create a Network Policy7. Create an SSID in which "Enable Captive Web Portal" is checked8. Choose the Captive Web Portal and the AAA Client for the "Authentication".9. Choose the default User Profile.10. Save the Network Policy11. Under a device configuration - choose the Network Policy and set the static IP address the AAA Client is pointing and choose the Aerohive AAA Server for Device RADIUS Service12. Complete Update

Unfortunatellly it is NOT possible.If you want to limit the number of concurrent users, you should use the private PSK instead of CWP with User Authentication.The private PSK can tied to a MAC address - like CID.